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The formula for a Hydrate  Hydrate – compound with a specific # of water molecules bound to its atoms  Naming:  name salt prefix hydrate  CaCl 2 2H 2 O calcium chloride dihydrate  Prefixes are the same as those used for covalent compounds (see page 338 for review)  Anhydrous – without water used to store water or as drying agents  Used to store solar energy i.e. sodium sulfate decahydrate

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Compound Nomenclature Binary compound Metal present yes no yes Use prefixes Does the metal form more than one cation? Use element name Use element name with proper Roman numeral no Polyatomic ion or ions present? yes Use the polyatomic name as appropriate noyes no Not established no yes Use Acid naming rules Is hydrogen the cation?

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Naming Compounds and Writing Formulas Acids start with hydrogen IF there is no oxygen, you name it with hydro – root – ic acid IF there is an oxygen, you change the ending of the polyatomic name - ate becomes –ic acid - ite becomes – ous acid Both contain polyatomics – KNOW them! Both formulas have to balance to zero Ionic compounds start with metals IF the metal is a transition metal, or P block metal then a Roman numeral is used to represent the charge (basically everything except the S block, Al, Zn, Cd, Ag, & Ga). Polyatomic names are not changed – just use the name. Covalent compounds start with nonmetals or metalloids Prefixes are used to identify the number of atoms for an element NEVER use mono on the first element The prefixes are: mono, di, tri, tetra, penta, hexa, hepta, octa, nona, and deca Binary compounds 1 st element uses name 2 nd element named with root and -ide You MUST KNOW your elements and their symbols!

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Common Mistakes  Not KNOWING the 14 polyatomics – correct formula and charges  Not KNOWING the charges of elements based on the periodic table.  Alkali metals are 1+, alkaline earth metals are 2+, aluminum is 3+, nitrogen group is 3-, oxygen group is 2-, halogens are 1-.  Transition metals (except zinc, cadmium, and silver) and metals in the P block have more than 1 charge.  Not putting the parentheses around hydroxide when there is more than 1.  OH 2 is water; (OH) 2 is 2 hydroxides  Not simplifying (if the charges are the same, no subscripts are needed)  Not using roman numerals correctly in the names.